The Financial Times says that block trades involve a bank buying discounted stock from large shareholders and then selling the shares at a higher price. They are trickier to price and have recently left bankers holding on to unwanted equity as they compete for deals.

'If you get the wrong price then it is going to be a difficult execution. I would categorise the price as very tight . . . Everyone looks at the price on the screen and asks: what discount are you offering me for this ?', a rival banker told the newspaper.